This invention concerns improvements in the manufacture and construction of composite surface elements, such as tiles and panels, having a natural stone facing. Such elements are intended for use, for example, in the cladding of walls, ceilings or other surfaces, in the manufacture of furniture, and in fact for all purposes where natural stone surfaces are required.
Natural stone, such as marble, is an exquisite surfacing material on account of its hardness and durability, beauty of structure and high polish which can usually be imparted to it, but its use is greatly restricted by reason of its weight and expense, since the material is liable to fracture if not of a certain thickness, depending upon the handling and usage to which it may require to be subjected. These drawbacks are overcome by the invention the subject of my U.S. Pat. No. 3,723,233, which describes and claims a marblefaced composite wall panel comprising a marble lamina 2 to 5 millimeters in thickness and bonded by adhesive to a backing consisting of a sheet of metal honeycomb structure 1 to 2 centimeters thick having a glass fiber skin on the side of said honeycomb opposite said marble lamina about 0.5 millimeter thick, the cell walls of said honeycomb being perpendicular to the plane of the sheet. The present invention is an improvement in, and modification of, the aforesaid invention in that the multicellular metal core is replaced by a multicellular paper core which is considerably cheaper to produce than the metal core while having to the degree necessary for most practical purposes the required qualities of lightness and strength.
My aforesaid U.S. patent also claims a method of manufacturing a marble-faced composite surface element comprising a marble lamina bonded by adhesive to a backing comprising a metal sheet of honeycomb or cellular structure of substantially greater thickness than said lamina and having a skin of tenacious sheet material of substantially less thickness than said lamina bonded to the backing on the side thereof remote from said lamina, comprising the steps of adhesively bonding to the surface of a marble slab a metal sheet of honeycomb or cellular structure reinforced by a skin of tenacious sheet material bonded to the side of said sheet remote from said marble slab, and thereafter sawing off a portion of said marble slab to leave a thin marble layer adhered to said metal sheet. The marble lamina may be severed from the slab using a diamond-toothed band-saw which cuts in a horizontal plane. However, conventional band-saws are designed to cut sheets of marble or stone of thickness much greater than 5 mm and they usually cut to an accuracy of about 1 to 2 mm. Such a margin of error is acceptable where the sheets being cut are relatively thick but it causes problems where the laminae are required to be cut to a thickness of between 2 and 5 mm. Any inaccuracy in cutting is usually reflected in the form of ridges or waves on the upper surface of the marble slab which causes problems in applying the backing. One way of overcoming this difficulty is to use an excess of adhesive which acts as a filler and makes up for any inaccuracies. However, this is an expensive procedure as a large amount of adhesive is required. It is a further object of the present invention to overcome this problem.